The JapaneseSocietyJapanese Society forforPlant Plant Systematics ISSN OOOI-6799 Acta Phytotax. Geobot. 48 (1): 15-21 (1997) Chromosomes of CaraUia, Gynotroches, and Pellacalyx (Rhizophoraceae; Gynotrocheae) KAZUO OGINUMA] and HIROSHI TOBE2 iCollege of enild Development, Kochi Women's U}iiversiry, l32 Ohara-cho, Kochi 780, Jopan; 2Flaculty ofIntegrated Human Studies, K)Joto U}ziversity, K>,oto 606-Ol, Japan Abstract. Tl)e chromesome number and karyomorphology of Carallia, Gynotroches, and Petlacalyx, all tribe Gynotrocheae of RhizopheTaceae, are reported for the first time on the basis of one or two species each and using somatic cells of young lcaves, [Hie chromosome nurnber is 2n=112 (probably an octoploid with x=14) in Carattia brachiata, 2n=28 (x==14) in Gynotroches axillarts, and 2n=26 (x=13) in Pellacalyx axillaris and P. saccardianus. Based oll comparisons with other Rhizophoraceae in cytological anti other characters, the pessibility is discussed that x=14 is an ancestral basic number for the tribe acquired in a comrnon ancestor with Crossostylideae (Crossostylis) (x==14) and Rhizophoreae (x==18), and that x== 13 is a derived one. Key words: CaraUin, ehromosome, Gynotrocheae, Gynotroches, PellacaLyx. Rhizophoraceae Received May 8, 1997; accepted June 22, 1997 Carallia (9 species), (lynotroches (2-4 species), and Pellacalyx (8 species), which are distributed from southern east Asia to the South Pacific islands and northern Australia (Juncosa and Tomlinson, 1988a), are all three genera of tribe Gynotrocheae of Rhizophoraceae. The family consists of 10 or 11 inland genera in three tribes (Crossostylidieae, Gynotrocheae, and Macarisieae) and four mangrove genera in one tribe (Rhizophoreae) (Tobe and Raven, 1988). Within Rhizophoraceae, these three genera, along with Crossostylis (Crossostylideae), are considered to occupy a pivotal position because they are related to primitive inland genera (Macarisieae) distributed in Africa, South America, and India, on the one hand, and to the most specialized, mangrove genera (Rhizo- phoreae), on the other (Juncosa and Tomlinson, 1988a; Tobe and Raven, 1988; Juncosa and Tobe, 1988). In contrast to other systematic characters that have been studied well and mostly published in symposium papers in the Annals qf the Missouri Botanical Garden (1988, Vol. 75, No. 4), the karyomorphological features of the family is still poorly documented (for review see Juncosa and Tomlinson, 1988b; Oginuma et al., 1992b). The cytology of the four mangrove genera as well as of several African inland genera are best known (e.g., Mangenot and Mangenot, 1958; Sidhu, 1968; Weiss, 1973; Yoshioka et al., 1984; Subramanian, 1988), and recently an intensive study of chromosome number and morphology of Crossostylis was published (Oginuma et al., 1992b). However, no chromosome information is NII-Electronic Library Service The JapaneseSocietyJapanese Society forforPlant Plant Systematics 16 Acta Phytotax. Geebet. Vol. 48 available for Carallia, (lynotroches and Pellacalyx. Materials and Methods Young leaves of Carallia brachiata (Lour,) Merr. (Oginuma 9222, Kyo; Shawn s. n., Kyo), Gynotroches axillaris Blume (Oginuma 9107, Kyo) and Pellacalyx axillaris Korth. (Shawn s. n., Kyo) and P. saccardianus Scortech. (Oginuma 9106, Kyo) were collected in Singapore. Somatic chromosomes were examined using at least three to five cells of the young leaves. Methods of pretreatment, fixation, and staining for chromosome observations followed those described by Oginuma et al. (1992a). Results Carallia brachiata Two collections from different places in Singapore showed the same karyomorphological features. The interphase nucleus (Fig.1) shows chromatin threads and many chromomeric granules. Eighty to 100 small (less than e.4ym in diameter), darkly staining, round or ellipsoid, condensed blocks also appear in the nucleus. Since such blocks are fewer in number than chromosornes, the interphase nucleus is of the simple chromocenter type (for typification see Tanaka, 1971), Chromosomes at mitotic prophase have the early condensing segments, which are confined to the proximal regions of both arms in most chromosomes and show a clear transition to the late condensing segments (Fig. 2). The chromosome number is 2n==112 and the chromosomes at mitotic metaphase are small, varying gradually from about O.4 Am long to about 1.3 #m long. Seventy-two of the 112 chromosomes have centromeres at median position (Figs.3,le). Of the 40 remaining chromosomes, eight have centromeres at subterminal or apparently terminal position, but the others are uncertain with respect to exact positions of centromeres. Gynotroches axillaris Interphase nucJear features look similar to those of Carallia, although Gynotroches axillaris has fewer condensed blocks (10 to 15) and more numerous faintly staining chromatin (Fig. 4). The interphase nucleus is of the simple chromocenter type. The morphology at mitotic prophase chromosomes is also similar to that of Carallia (Fig. 5). The chromosome number is 2n=28 and the chromosomes at mitotic metaphase vary gradually from about O.4 ptm long to about O.8 ym long. Eighteen of 28 chromosomes have centromeres at median position (Figs. 6, 11). Of the ten remaining chromosomes, two have centromeres at subterminal or terminal position, but the others are uncertain with respect to exact positions of centromeres, NII-Electronic Library Service The Japanese SocietySoolety for Plant SystematicsSystematlos August 1997 0GINUMA ＆ TOBE Chromosomes ot Gynotrocheae 17 ” 嫐 姻 抽 …蠱 転 『 ． 睾 轡 ー 葬 藪輳 鱒 ま 謬 麟 梅 麁 轟 霜 …涯 ー 鴫 闘 忌 “ 轄 l」 蜘 蠻・ 靉 ミ 謎 鎌、 。 〆 犠 灘囓 瀦 li雑 癖灘 嘸 1癒巉 蝿 − FIG 1 Somdtlc chromosomes at lnterphase 1 斗 7 2 5 8 and metaphase 3 6 9 ln 9 （， ， ）， prophasc （，，） （．，） − ＝’ − Gy 】10trocheae （Rhlzophoraceae ） 1 3 Cara 〃la brachiata （2n 112） 4 6 G ンnottoches exdlarts ＝ − ＝ ＝ （2n 28） 7 9 Pellacal．＞x saccardianus （2n 26） Scalc b4r 2 μ nl 一 NII-ElectronicN 工 工 Eleotronlo LibraryLlbrary Service The JapaneseSocletyJapanese Society forforPlant Plant Systematics 18 Acta Phytotax, Geobot, Vol. 48 t ttt t t/ / / t / tt /lt tlt /t/ t ec fa ge $ ,, 1 s･ gk,tilllge ･ a tsj ge Xi,Xi x ec i :si Xaj ' pt g i･iSii' ･ "' s ･ l,,II,l:i,gf}Sl, ;g\e, fk･1itlli igfg/klr //ff. i FIG. 10-12, Drawings of somatic chromosomesX ar metaphase of three species im Gynotrocheaeki, (Rhizophoraceae). Ie, Caratlia brachiata (2n:=112),' 11: Gynotroches axiltaris (2n:=:28). 12: Pellacalyx saechardianus (2n=26). Arrows pomt out chremesomes with centromeres at subcerminal or terminal position, Scale bar==2 ptm. Pellacalyx axillaris and P. saccardianus The two species examined have the same number 2n=26. The inter- phase nucleus (Fig.7) and prophase chromosome morphology (Fig. 8) resemble those of Gynotroches. The interphase nucleus is of the simple chromocenter type. The chromosomes show gradual decreases in size; the shortest chromosome is about O.6ym, and the longest chromosome about 1.2ym. Of the 26 chromosomes, 24 have centromeres at median position, and the remaining two have them at subterminal or terminal position (Figs. 9, 12). Discussion As presented above, Carallia, Gynotroches, and Pellacalyx have similar chromosome features at interphase and prophase. We can deter- mine x== 14 for GynotToches and x==13 for Pellacalyx. For Carallia two possibilities exist concerning the basic number of the genus on the basis of C brachiata (2n=112): that is, an octoploid of x=14 or a heptaploid of x =16. Considering the fact that Carallia brachiata sets well fertile seeds, F the possiblity is more likely that 2n=112 is the octoploid with x=14. Comparisons with other Rhizophoraceae In Table 1 the basic chromosome number and karyomorphology (in terms of the frequency of chromosomes with centromeres at subterminal or NII-Electronic Library Service The JapaneseSocietyJapanese Society forforPlant Plant Systematics August 1997 OGINUMA & TOBE: Chromosomes of Gynotroeheae 19 TABLE 1. A summary of chromosome features ef Rhizophoraceae, Classification fo11ows Tobe and Raven (1988). The nurnber of choromosomes with subterminal or terminl centromeTes (st-t- chromosDrnes) is indicated as u numerator, and the basic number as a denominator. Chromosomenumber Frequency Tribelgenus Reference 2nx st-t-chromosomes Macarisieae Anopyxts 64 ]6?16????????,? Mangenot and Mangenot (1958), Weiss (1973) Blcpharistemma Cassipourea 64 Mangenot and Mangenot (1958), Weiss (1973) Comiphyton Macarisia Sten'gmapetalum Crossostylideae Crossostytis 28 14 2114 (14%) Oginuma et al. (1992b) Gynotrocheae CaraUia 1122826141413 ??1/13 This study Gynotroches 1[1iis study Pellacalyx (8%) This study Rhizophoreae Bruguiera 36 18 ? Sidhu (1968), Weiss (1973),Yoshioka et at. (1984) Ceriops 36 18 8/18 (33%) Sidhu (1968), Weiss (1973),Yoshioka et al. (1984), Subramanian (1988) Kandelia 3636 1818 ?6-8I18 Yoshioka et at. (1984) Rhizophora (33-44%)Sidhu (1968), Weiss (1973),Yoshioka et al. (1984), Subrarnanian (1988) terminal position) in (JZirallia, Gynotroches, and Pellacalyx are summarized and compared with those of the other Rhizophoraceae. differences are found in the basic Throughout the whole family, number as well as in the frequency of chromosomes with cerntromeres at rllhe subterminal or terminal position. basic number x=14 is restricted to Gynotrocheae (Carallia and Gynotroches) and Crossostylideae (Crossosty- lis), while x=16 and x=18 are characteristic of Macarisieae and Rhizophoreae, respectively. Rhizophoraceae are placed in Rosidae, but its relationships with other families are still uncertain (for most recent review